Percussive motor



Feb. 26, 1929 L. A. MAXSON PERCUSSIVE MOTOR Filed Jan. 1920 2 Sheets-Sheet 1' Feb. 26, 1929. 1,703,840

L. A. MAXSON PERCUS S I VE MOTOR Filed Jan. 1920 2 Sheets-Sheet 2 i/ZM/Y/ Patented Feb. 26, 1929.

UNITED STATES PATENT OFFICE. v

LOUIS A. MAISON, OF CLAREMONT, NEW HAMPSHIRE, ASSIGNOR TO SULLIVAN MACHINERY COMPANY, A CORPORATION OF MASSACHUSETTS.

PEBCUSSIVE MOTOR.

Application filed January 2, 1920. Serial No. 349,018.

My invention relates to percussive motors. Its object is to provide an improved percussive motor. A further object of my invention is to provide an improved motor in which the supply of fluid for a stroke in either direction is more expeditiously delivered than in motors heretofore constructed, and in which, simultaneously, I have avoided the production ofexcessive cushioning pressures by delaying admission of a large part of the charge of motive fluid until substantially the beginning of the stroke in either direction. Another object is to so combine the features of valved and valveless motors as to obtain freedom from theexcessive preadmission found in valveless tools while using features of valveless construction to secure just the desired degree of cushion, and to increase the capacity of the motor above the limits imposed by the relation of admission to cushion in valveless toolsand by port size in valved tools. A further object of my invention is to admit and store up fluid pressure for use in the cylinder during the period at about the middle of the traverse of the piston in either direction when flow through the inlet port is reduced to much less than at other times in valveless tools. Other objects of my invention-will be apparent from the following specification and the appended claims.

In the accompanying drawings, I have shown, for purposes of illustration, three forms which my invention may assume in practice.

5 In these drawings 1 represents a developed section on the broken line 11 of Fig. 2, certain parts of the motornot constituting per se a part of my invention, being shown in elevation.

Fig. 2 is a section on line 2-2 of Fig. 1.

Figs. 3 and 4am partial sectional views showing modified embodiments.

In these drawings-I have shown a percussive motor having a cylinder member indicated generally by 1, which is closed at opposite ends by heads 2 and 3 to which are respectively attached a chuck housing 4 and a throttle valve 5. The cylinder is provided with a bore of uniform diameter 6, and within the cylinder reciprocates a piston 7 having heads of like length 8 and 9, and between these heads is provided. a reduced portion 10. Around this reduced portion 10 is an annularspace 11 which is adapted to cooperate with suitable ports, hereinafter described, in the fluid distribution to the cylinder. Extending longitudinally within the walls of the cylin der are inlet passages 13, to which fluid is supplied from any suitable source under control of the throttle valve 5. The inlet passages 13 are provided with ports 14 opening directly into the cylinder midway of its length, the length of the groove in the piston being suf flcient to leave the inlet port full open in either extreme position of the piston. Cooperating with this inlet port-are fluid supply passages 15 and 16, which open into the cylinder on opposite sides of the inlet port by means of ports 17 and 18, these ports being. separated by such distance that either ports 17 or ports 18 are always at least in partial communication with the inlet ports 14, and passages 15 and 16 open into the opposite ends of the cylinder through ports 19-and 20, respectively. The construction so far described is well known save for the somewhat smaller size of the passages 15 and 16.

Cooperating with the inlet port and distribution passages described hereabove, I have arranged a port 22 at the opposite side of the cylinder, and cooperating with this port is a valve 23 adapted to control the supply and the distribution to the cylinder from two series of storage chambers 25 and 26, the separate chambers of which communicate with each other by passages 25' and 26. The valve which I have illustrated is of the four-spool type, the spools being indicated, respectively, by 27, 28, 29, and 30. The valve is mounted in a valve cylinder 32 of such length that the port formed between the spools 28 and 29 always communicates with the port 22 and alternately with the sets of ports 33 and 34 communicating with the storage chambers 25, 26. Arranged at the outside of the ports 33, 34, are a pair of passages 37' and 38 opening into the opposite ends of the cylinder by means of ports '39 and 40 and opening into the valve chamber adjacent the ports 33, 34 by means of ports 41 and 42.

It will be understood that the proportioning of the sizes of various parts will be such as to, in practice, best effect the desired results, but I have herein shown the valve as of a relatively large size for purposes of clarity of illustration.

To effect the throwing of the valve 23, I- have'provided at the ends of the valve chamber 32, ports 43 and 44 openlng into the bore of the cylinder in such position as to be heads slight the inner faces of the piston y before the piston reaches the end of its strokes and immediately before the exhaust ports (hereafter described) are opened. These ports communicatewith the extreme ends of the valve chambers 32 by passages 47 and 48, and communicating with these passages are further ports and 46 so uncovered by 7 located as to be cleared by the outer ends of .the valve 23- is started towards its other position due .to the action of live fluid through the port 44 or 43 on one end andexpanded fluid on the other, and the throw is completed when the exhaust port 51 or 52 is opened.

' What is accomplished here is the closure of communication between the expansion chambers and the ends of the cylinder before the latter are opened to exhaust. This prevents the loss of the fluid which hasnot been fully expanded in the storage chambers.

The operation of the form of my invention disclosed for purposes of illustration in Figs. 1 and 2 is as follows: Fluid pressure is admitted through the inlet passage 13, enters the cylinder through the port 14, and is conducted to the right hand or forward end of the cylinder in Fig. 1. Fluid simultaneously passes through the port 43 and into the valve chamber 32 at the right hand end thereof and holds the valve 23 in the position shown in Fig. 1. As no fluid has previously been stored in the storage chamber 25, the admission through the passage 15 will cause the piston to start to the left. Fluid is likewise simultaneously passing through the port 22, through the space between the heads 28 and 29 in the spool valve, and into the storage chambers 26, which will accordingly be filled with fluid under pressure. When the piston overruns the port 18, fluid will begin to pass through the passage 16 into the left hand end ofthe cylinder, but a suflicient pressure to check the piston. will not build up therein until about the completion of the stroke. It

' will here be noted that fluid entering either end of the cylinder immediately after the ports 17 or 18 are opened, will have its cushioning efl'ect minimized by the volume of the passages 37 or 38 which communicate with c the end of the cylinder. l/Vhen the port 45 is uncovered by the right hand end of the piston, the pressure in the right end of the chamber 32 will drop as this chamber then communicates with the right hand end of the cylinder wherein expansion has reduced the pressure to a certain extent. The valve 23-3 will thus start to move over and will close communication between the por s and 41 before the port 51 is opened, it being noted that the port 44 is so located as to be uncovered before the exhaust port 51 opened. This will serve to save unexpanded fluid in the storage chambers during normal operation of the motor. During this first stroke, of course, the chamber 25 contained only such pressure as passed to it through the passage 15. The throw of the valve is completed by the end of the piston stroke. Upon the throwing of the valve 23 and the connection, by the passage between the heads 27 and 28 of the valve 23, of the storage chambers 26 with the passage 38, the large charge of stored fluid will be at once connected with the end of the cylinder and aid in causing a forward stroke of great speed and force due to the large volume of pressure fluid conducted to the cylinder. As the 1 iston moves to the right upon this stroke. flu d will again be admitted through the passage 15 to the right hand end of the cylinder when the port 17 is un covered by the piston, this pressure, however, not buildlng up a suflicient pressure in the cylinder to unduly cushion the'blow. when the piston nearly reaches the end of its travel in the right hand direction, the ports 46 and 43 will be opened and the valve 23 shifted by the difference in pressures on its ends, and the exhaust port 52 will also beoverrun. The fluid stored in the chamber 25 during the forward stroke will then pass to the cylin-' der. It will be obvious that means is provided in this motor whereby fluid may be stored for use to effect a stroke in either direction during thev substantially entire previous stroke in the opposite direction, and whereby a large'quantity of motive fluid may be admitted to the cylinder at the desired stant, i. e., at the beginning of a stroke, to

effect quick movement of the piston. An-

other beneficial result isthat while a motor which is positive in starting from any posi tion is provided, it has not been necessary to so proportion the several. parts that an excessive pre-admission will occur. A further advantage lies in the fact that by the throwing of the valve 23, as described, the partially expanded fluid contained in the storage chambers is not lost when the'exhaust ports open, but is preserved, by the cutting of? of the storage chambers from communication with the cylinder prior to the opening of the exhaust ports, for use when supplemented on a later stroke. f

It will be further noted that I have illus tion being controlled by the valve 23, in which case cushioning will be reduced to a minimum. It will be obvious, further, that either of the valves may be partially closed while the 7 other remains open, thereby adjusting cashioning at eitherend as may be desired. For example, by entirely closing the valve 61, it will be possible to cause the striking of an almostentirely uncushioned blow, but by leaving the valve 62 open a cushion may be maintained at the rear end of the cylinder. It will be understood. however, that the provision of the valves 61 and 62 is no wise essential.

In Fig. 3 I have shown another modification which may be given to the ports and 16, these ports being considerably enlarged between their ends to form expansion cham hers 71 and 72 to thereby delay building up of pressure in the ends of the cylinders and to provide a storage reservoir from which a greater charge of fluid may be admitted to perform the stroke. In this case, the ports 17 and 18, and 19 and 20 may be materially enlarged and a very owerful action obtained.

In Fig. 4 I have shown a still further modification which this invention may assume in practice. In this form the passages 15 and 16 are provided of much greater size than in the form shown in Fig. 1, and the ports .17

and 18 are removed from the inlet port a the ports 15 and 16. and accordinglyfluid admitted through them will be conducted to the ports 15 and 16 and enable the starting of the motor. When the motor gets up to speed. however. the area of these ports is so small that they do not substantially influence the speed of the tool.

' While I have in this application specifically described three embodiments which my invention may assume in practice, it will be understood that the same are shown for purposes of illustration only,'and that the invention maybe modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

hat I claim as new' and'desire to secure by Letters Patent is:

1. In a fluid pressure percussive motor, a cylinder, a piston therein, fluid distribution means comprising an inlet port, fluid storage means. means whereby fluid to be used at one end of said cylinder is admitted through said inlet port to said storage means during substantially an entire stroke towards that end and whereby said fluid storage means is then placed in communication with said end of the cylinder, and means whereby fluid is admitted through said inlet port and conductedte the other end of the cylinder simultaneously with the admitting oi fluid for thefirst mentioned end. a

2. In a fluid pressure percussive motor, a cylinder, a piston therein, and means for supplying fluid to efi'ectmovement of said piston in said cylinder comprising an inlet port, passages controlled by said piston to conduct fluid pressure to the ends ofsaid cylinder, and supplemental fluid pressure supply means for each end or" said cylinder connectible each with its respective end of the cylinder and placed in communication with said inlet port prior to the opening oisaid piston controlled passages.

.3. In a fluid pressure percussive motor, a cylinder, a piston therein, fluid supply, exhau. Land distribution means for said cylinder, said fluid distribution means comprising a storage chamber communicable with one end of. said cylinder. and means to interrupt said communication prior to the opening of the exhaust from that end of said cylinder.

4-. In a fluid pressure percussive motor, a cylinder, a piston therein, an inlet port fluid distribution ports controlledby said piston for the supply of fluid pressure tothe ends of the cylinder, and means to supplement the supply of fluid pressure thereto comprising fluid storage means and means for supplying the-same with fluid pressure wide open at a time when the supply -to said distribution ports is at a minimum. v 5. In a fluid pressure percussive motor, a cylinder, a piston therein having a pair of heads separated by an annular groove, an inlet port opening into said cylinder adjacent the center thereof, a port opposite said inlet port, a storagechamber communicable with said cylinder by means of said opposite port, and means for charging said storage chamber during one pass of the piston, discontinuing chargingat the end of said pass, and discharging it to the end of said cylinder on the next successive pass.

6. In a fluid pressure percussive motor, a

cylinder. a piston therein, an inlet port, a pair of fluid pressure storage chambers communicable respectively with the opposite ends of the cylinder, and means including means for interrupting communication between said chambers and the ends of said cylinder whereby said storage chambers are charged'with fluid pressure on alternate passes of the piston, and connected with opposite ends of the cylinder during the intervals between chargings.

7. In a fluid pressure percussive motor, a cylinder, a piston therein, an inlet port and fluid distribution means cooperating therewith, additional fluid distribution means comjrisin stora e chambersand a valvecoo cr-- ating therewith whereby fluid to be used at one end of said cylinder is admitted through i said inlet port to one of said storage chambers during the interval when supply to the" same end of the cylinder through said first mentioned fluid distribution means is at a minimum.

8. In a. fluid pressure percussive motor, a cylinder-,a piston therein, an inlet port,'fluid distribution passages controlled by said piston, and means for supplementing the fluid supply throughsaid piston controlled passages including a storage chamber adapted to bebrought into communication with an end 'of'the cylinder at the. instant the piston reaches that end. H

9.7 In ZLfilllCl pressure percuss ve motor, a

cylinder, a piston therein, an inlet port, passages controlled by said piston to conduct fluid pressure to the ends of said cyl nder, a

supplemental fluid distribution systemv in-- cluding a pair of storage chambers, av valve controlling thecon'nnunication of the same with the fluid pressure supply and with the opposite ends of the, cylinder, and means for throwing. said valve controlled by said piston. 1.0. Ina fluidpressure percussive motor, a

- cylinder, a piston therein, an inlet port, fluid distribution means controlled by said piston to-conduct fluid pressure to the ends of said cylinder, and supplemental fluid pressure supply meanscontrolled by said piston whose communication with said ends of said cylinder is opened and closed subsequent respectively to" the opening and closing of said first mentioned piston controlled means.

11. In afluid pressurepercussive motor, a

cylinder, a piston therein, a fluid distribution system controlled by said piston, and a supplemental fluid distribution system comprising a pair of fluid storage chambers commit ni'cable each with one end of said-cylinder and closed thereto prior to the opening of an exhaust from its respective end of. said cylinder.

12; In a fluid pressurepercussive motor, a cylinder, a piston having a pair of heads separated by an annular groove, an inlet port,

fluid distribution ports adapted to beconnected in alternation with said inlet port by said groove and leading to opposite ends of said cylinder, a .port circumferentially spaced from said inlet port but in the same transverse plane, a pair of storage chambers, a pair of passages communicating with the ends of said cylinder, anda piston cont-rolled valve adapted to connect said storage chambers alternately with said secondanentioned port and with said passages; l

13. In a fluid pressure percussive motor, a cylinder, a piston therein, said cylinderhaving a valve controlled fluid pressure distribution system and piston controlled exhaust ports, and a supplemental distribution systenrcomprising passages adapted to be con-' nected 1n alternation to said fluid pressure cylinder, and means to vary the cushion produced by fluidpassing tlirough these ports including a valvelocated-between the ends of each of them.

15. In a fluid pressure percussive motor, a

cylinder, a piston therein, an inlet port, a fluid pressure distribution system controlling the supply of'fluid tooppositelends of said cylinder at the instant when the piston reaches said ends, a supplemental distribution system comprising means for admitting fluid pressureto the ends of said cylinder prior to the moment when said piston reaches said ends, and means to minimize the cushioning action occasioned bysuch pre-admission including valves controlling said supplemental means. 7

In testimony whereof I affix my signature.

LOUIS MAXSON. 

